A conventional navigation apparatus displays on a road map characters showing names of various kinds of facilities, natural features, roads, and so on, in addition to names of administrative districts such as prefectures, cities, towns, villages. The characters are stored in advance, as image data having different font sizes or outline font data. The characters are displayed by using the image data or outline font data.
Here, since the image data or outline font data shows characters of only one font type, the conventional navigation apparatus changes the colors or sizes of the characters in purposes of highlighting and differentiating the characters in accordance with categories of the objects shown thereby.
However, in a case where the colors of the characters are changed, since the roads are indicated with the different colors depending on the road categories (toll road, national highway, city road, or the like), if the color of the character assimilates to one of the road colors, it results in inferior character recognition.
As for the size of the character, it is difficult to change the sizes of the characters on an operating page, such as a menu page of the navigation apparatus, for setting or performing various kinds of functions of the navigation apparatus.